ls shoots to redline at startup

[toddmsc]

k so i bought an ls very recently just block, head and alt....i put in in my car using my intake and exhaust manis.....never had this problem with old motor

guy said it has a high rev on start up but goes down after it warms up

also said he got it from lsdb1 who can vouch its a good motor

but when i started it up it shot to redline, i shut it off

throttle cable isnt stuck flap is closed no vacuum leaks

please help need to fix it asap

[leo2006leo]

Nna say throlle cable jst check it or u brought a fucked up block. But g.l bro

[toddmsc]

throttle cable is fine

i know the block is good sounds strong as h3ll but need to figure out this idle problem

[lsvtecrex]

dude i never said it idles high then goes down...it idles up when cold just like any other engine then idles down,,it was idleing and running fine when it came out..sounds liek u have a vaccum leak did u buy a new intake gasket??

[injen78]

he reused his intake gasket..he told me it had broken intake gasket on the surface and i told him to scrape it off and try again lmao..
he said timing is dead on,vacuum hoses are fine,everything is fine just revs way high..
if i would have done the swap it woulda been perfect lmao

[doitpropa]

yea that motor is deffinetly mint

[LS/Vtec]

sounds like you fucked something up when you put it in.

[delsoleg1]

sounds like tha iacv is stuck open big time

[lsvtecrex]

yeh something is messed up from the installl....... or maybe the iacv could be stuck but its not the engine

[Spoon6]

im gonna vouch for the iacv or vaccum leak personally!

[spoon860]

sounds like u got a leack in the intake manni... take the manni off and make sure ther is absolutly nothing.. it needs to be a clean metal surface on both the head and block, and use a new gasket... same problem with a ls i did in a eg. a small peice of the old gasket stood stuck on the head and it didnt let it seal right

[NHSwaps13203]

prolly no gasket lmfao

[injen78]

its got a gasket and he cleaned the surfaces..timing was off a tooth as well..fixed it and still nothing..plugged both holes in the TB and it still does it..he told me he unplugged some sensor on the intake and it now it jumps to 2500 and rev limit kicks in..so thats a CEL
im gonna look at it maybe today

[injen78]

he said when he unplugs the iacv it will idle at 1200 and he can rev it normal..ive never heard of an iacv going bad and causing the car to jump to redline though..the most ive seen is hunting from idle to about 3k rpm...

[LS/Vtec]

Damn race car status, You dnt even have to hit the gas.